The present invention relates to a planetary roller gear drive that converts a relative rotation between the spindle nut and threaded spindle into a translational relative displacement between the spindle nut and threaded spindle.
From DE 102009040606 A1, a planetary roller gear drive is known that is provided with a plurality of planets that are arranged distributed about the periphery and are in rolling engagement with the threaded spindle and the spindle nut, wherein the threaded spindle has a plurality of helical windings wound about the spindle axis in at least one threaded groove. The spindle nut is provided on its inner periphery with a nut-side profile, wherein the planet-side profile of the planets is in rolling engagement with the nut-side profile. The planets are provided with annular, closed grooves that are arranged perpendicular to the planetary axis. The planets revolve on orbits that are arranged perpendicular to the spindle axis.
Slippage between the threaded spindle and spindle nut can be observed when such planetary roller gear drives are operating.
According to DE 102009040606 A1, a longitudinal measurement system is provided for determining the position. This system has a sensor that is connected rigidly to the spindle nut and scans the threaded spindle. The sensor detects the advancing windings of the threaded groove, wherein the threaded spindle is used as a dimensional body for determining an axial position of the spindle nut and threaded spindle relative to each other.
For an improved position determination, DE 102009040606 A1 also provides a rotary encoder that is formed as an absolute value encoder and indicates an absolute angular position of the threaded spindle.